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The Advanced Infra-Red WAter Vapour Estimator (AIRWAVE) algorithm [Casadio et al. (2016)] exploits the dual view of the Thermal Infrared channels of the ATSR instruments and a sea surface emissivity dataset to compute the Total Column of Water Vapour (TCWV) over water in clear sky conditions. 20-years of day-night TCWV dataset have been produced applying AIRWAVE to the measurements of the Along Track Scanning Radiometer (ATSR) missions. AIRWAVE has been developed for observations over water surfaces but the algorithm can also be applied to land surfaces. The main difficulty in exploiting land measurements is linked to the knowledge of the surface emissivity in the ATSR infrared channels. While sea emissivity is generally close to one and is almost constant all over the globe, land emissivity has strong variations depending on e.g. surface type and vegetation cover. Furthermore, the angular emissivity variations can also be relevant. For the extension of the AIRWAVE algorithm to land surfaces, one strategy is the use of tabulated emissivity datasets. The limitations of these datasets is that they report data relative to only daytime (ATSR measures both day and night) and the data are averaged over long time spans (tenth of days). Another strategy is the use of retrieved emissivities from instruments covering the same spectral region of the TIR channels of ATSR and measuring almost at the same time. Recently Masiello et al. (2013-2015) have developed a retrieval scheme to obtain the Land Emissivity from SEVIRI observations. SEVIRI measures on board the geostationary satellite Meteosat and two of its channels superimpose to the TIR channels of ATSR. Therefore, SEVIRI and AATSR/ENVISAT represent a perfect match to test the possibility of a joint analysis to get both land emissivities and TCWV. In this work we will show the results of the application of the AIRWAVE algorithm to measurements over land. We will critically compare the results obtained using emissivity databases and the SEVIRI retrieved emissivities, assessing their performance through the comparison of the obtained results with correlative data contained into the ESA DUE GlobVapour project (http://www.globvapour.info/). Casadio S., et al. (2016) Remote sensing of Environment, doi:10.1016/j.rse.2015.10.037 Masiello G., et al. (2013), Atmos. Meas. Tech., doi:10.5194/amt-6-3613-2013 Masiello G., et al. (2015). Atmos. Meas. Tech., doi:10.5194/amt-8-2981-2015.

Lee waves are internal gravity waves which are produced when a stably stratified flow is forced over an obstacle. They are nowadays a well-recognized cause of hazard to aviation, especially under dry condition, when they are not clearly visible. They may also impact the global circulation and the climatological momentum balance, because of their interaction with high mountains, causing non-linear perturbations which may, in turn, interact with the larger-scale flow. The AIRWAVE (v1 and v2) datasets contain 20-years of day-night Total Column of Water Vapour (TCWV) over water surfaces at the ATSR native 1x1 km2 spatial resolution grid, allowing the investigation of small scale features as the lee waves. We focused our analysis on the Mediterranean region, which is the largest semi-enclosed basin on the Earth. The peculiarities of this area, characterized by complex orography and rough coastlines, may indeed lead to the development of such phenomena. For this purpose, the Mediterranean area was divided in three regions. To identify the regions characterized by lee waves we considered the AIRWAVEv2 TCWV products within an "optimized" latitude/longitude grid. For each grid point, the standard deviation was then computed and used as a proxy for the detection. The classification has been based on the number of grid points having a TCWV standard deviation exceeding a defined threshold. The atmospheric conditions which lead to the lee waves development were identified using the ECMWF wind fields at the finest resolution 0.125°x0.125° (10 metre U wind component, 10 metre V wind component every 6 hours). During the work it was clear that day time ATSR overpasses may sometimes be affected by wrong cloud mask classification. To overcome this problem, a cloud masking classification based only on ATSR infra-red channels was applied, and new TCWV values have been obtained from the re-analysis of these data. Here we show some examples of lee waves detections, comparing the AIRWAVEv2 TCWV fields with measurements from other sensors, e.g. from Synthetic Aperture Radar (SAR) observations, and with atmospheric model output from Weather Research and Forecasting (WRF) model. The application of the AIRWAVE algorithm to the current sensors, e.g. to Sentinel 3 SLSTR, would enable the extension of this study to a longer time period.

The Far-infrared-Outgoing-Radiation Understanding and Monitoring (FORUM) mission concept, selected by ESA for the feasibility study of the Earth Explorer 9 (EE9) will have to evaluate of water vapor and temperature profile precision and accuracy from FORUM observations in the wavelength range of 7 - 100 micrometers. These observations are important because Earth's infrared emission to space is affected by water vapor and cirrus clouds, which, in turn, play key roles in Earth's temperature. The characterization of the radiative effects of the main atmospheric components in this spectral range is a new measure from space, as it fills the observational gap in the far-infrared (FIR) region from space. In the framework of the FORUM mission, the Kyoto protocoL Informed Management of the Adaptation (KLIMA) algorithm has been used to simulate the FORUM wide-band spectral radiance measurements, with the aim to assess the water vapor and temperature profile precision and accuracy obtained using the Fourier Transform Spectrometer (FTS) observations and to evaluate the quality of the retrieval. The algorithm consists of two distinct modules, the Forward Model (FM) and the Retrieval Model (RM). The FM is a line-by-line radiative transfer model, with capability to simulate wide-band spectral radiances from 100 to 1600 cm-1 (i.e. the FORUM spectral range requirement); the RM uses a constrained Nonlinear Least Square Fit (NLSF) approach and the cost function to be minimized takes into account the a priori information (optimal estimation method) and the Marquardt parameter. We performed several tests to retrieve temperature and water vapor profile, using different quantifiers to assess the quality of the retrieval. In this work, we describe the strategy adopted for the analysis and we show first results of these evaluation activities.

One of the major limitations in climatic change predictions is the lack of an accurate modelling of the radiative processes related to atmospheric water vapour and clouds, and surface emissivity. Whilst the broadband mid-infrared spectrum is currently measured from space, our ability to unequivocally link the outgoing radiation to the underlying atmospheric processes is under-constrained because of the lack of spectrally resolved measurements over a significant portion of the thermal emission, the far infrared (FIR) between approximately 100 and 667 cm-1 (100-15 microns). Observations in the FIR can reduce the existing uncertainties about the role of water vapour, clouds, and the surface in climate models because of the strong sensitivity of the FIR region to these parameters. FORUM (Far-infrared-Outgoing-Radiation Understanding and Monitoring) has been selected by ESA to compete to be next Earth Explorer 9 mission. FORUM aims to fill the long-standing gap in FIR spectral observations from space. The mission will measure the spectrum of the Earth outgoing long-wave radiation (OLR) and provide an accurate basis for the detection of the spectroscopic fingerprints (due to water vapour, clouds, methane, carbon dioxide, and the snow surface emission) associated with processes relevant to climate change estimations. FORUM will measure the OLR from 100 to 1600 cm-1 with a nominal resolution of 0.3 cm-1 and an absolute accuracy of 0.1 K. By flying in tandem with the Meteorological Operational Satellite - Second Generation (Metop-SG), FORUM measurement will complement mid-infrared spectral measurements performed by the Infrared Atmospheric Sounding Instrument Next Generation (IASI-NG). In this way the complete characterisation of the Earth's OLR spectrum from 100 to 2760 cm-1 (3.62-100 mm) will be provided for the first time. The proposed satellite payload is composed of two main units: a Fourier transform spectrometer, operated with uncooled detectors, for the FIR spectral measurement and an infrared imager, observing the same scene in the 10.5-12 microns atmospheric window with a high spatial resolution, to provide cloud scenes identification. In this presentation, a description of the FORUM mission and the current development status will be discussed.

During the first perijove passage of the Juno mission, the Jovian InfraRed Auroral Mapper (JIRAM) observed a line of closely spaced oval features in Jupiter's southern hemisphere, between 30°S and 45°S. In this work, we focused on the longitudinal region covering the three ovals having higher contrast at 5 μm, i.e., between 120°W and 60°W in System III coordinates. We used the JIRAM's full spectral capability in the range 2.4-3 μm together with a Bayesian data inversion approach to retrieve maps of column densities and altitudes for an NH3 cloud and an N2H4 haze. The deep (under the saturation level) volume mixing ratio and the relative humidity for gaseous ammonia were also retrieved. Our results suggest different vortex activity for the three ovals. Updraft and downdraft together with considerations about the ammonia condensation could explain our maps providing evidences of cyclonic and anticyclonic structures.

The electromagnetic radiation emitted by the Jovian aurora extends from the X-Rays presumably caused by heavy ion precipitation and electron bremsstrahlung to thermal infrared radiation resulting from enhanced heating by high-energy charged particles. Many observations have been made since the 1990s with the Hubble Space Telescope, which was able to image the H2 Lyman and Werner bands that are directly excited by collisions of auroral electrons with H2. Ground-based telescopes obtained spectra and images of the thermal H3+ emission produced by charge transfer between H2+ and H+ ions and neutral H2 molecules in the lower thermosphere. However, so far the geometry of the observations limited the coverage from Earth orbit and only one case of simultaneous UV and infrared emissions has been described in the literature. The Juno mission provides the unique advantage to observe both Jovian hemispheres simultaneously in the two wavelength regions simultaneously and offers a more global coverage with unprecedented spatial resolution. This was the case....

The Jovian Infrared Auroral Mapper (JIRAM) is an imager/spectrometer on board NASA/Juno mission for the study of the Jovian aurorae. The first results of JIRAM's imager channel observations of the H3+ infrared emission, collected around the first Juno perijove, provide excellent spatial and temporal distribution of the Jovian aurorae, and show the morphology of the main ovals, the polar regions, and the footprints of Io, Europa and Ganymede. The extended Io "tail" persists for 3 h after the passage of the satellite flux tube. Multi-arc structures of varied spatial extent appear in both main auroral ovals. Inside the main ovals, intense, localized emissions are observed. In the southern aurora, an evident circular region of strong depletion of H3+ emissions is partially surrounded by an intense emission arc. The southern aurora is brighter than the north one in these observations. Similar, probably conjugate emission patterns are distinguishable in both polar regions.

We report the first spectroscopic identification of high altitude ammonia ice clouds observed in three discrete oval structures in the atmosphere of Jupiter by the Jovian InfraRed Auroral Mapper (JIRAM]) on board the Juno spacecraft. The ovals are observed at stationary positions in 2.57 micron radiance maps derived from JIRAM's spectrometer channel data acquired on Aug 2th 2016 (observation phase #2) and Aug 25th 2016 (#3) during Juno's first perijove passage. A quantitative analysis of these three features is performed by means of an inversion technique based on Bayesian method.

The Jupiter InfraRed Auroral Mapper (JIRAM) aboard Juno observed the Jovian South Pole aurora during the first orbit of the mission. H3+ (trihydrogen cation) and CH4 (methane) emissions have been identified and measured. The observations have been carried out in nadir and slant viewing both by a L-filtered imager and a 2-5 μm spectrometer. Results from the spectral analysis of the all observations taken over the South Pole by the instrument are reported. The coverage of the southern aurora during these measurements has been partial, but sufficient to determine different regions of temperature and abundance of the H3+ ion from its emission lines in the 3-4 μm wavelength range. Finally, the results from the southern aurora are also compared with those from the northern ones from the data taken during the same perijove pass and reported by Dinelli et al. (2017).

The IAPS experience in the field of analysis of planetary atmospheres from visual and infrared measurements dates back to the early '90 in the frame of the IFSI participation to the Mars96 program. Since then, the forward models as well as retrieval schemes have been constantly updated and have seen a large usage in the analysis of data from Mars Express, Venus Express and Cassini missions. At the eve of a new series of missions (Juno, ExoMars, JUICE), we review the tools currently available to the Italian community, the latest developments and future perspectives. Notably, recent reanalysis of PFS-MEX and VIRTIS-VEX data \citep{Grassi2014} leaded to a full convergence of complete Bayesian retrieval schemes and approximate forward models, achieving a degree of maturity and flexibility quite close to the state-of-the-art NEMESIS package \citep{Irwin2007}. As a test case, the retrieval code for the JIRAM observations of hot-spots will be discussed, with extensive validation against simulated observations.

JIRAM (Jovian Infrared Auroral Mapper) is an imager/spectrometer on board Juno. One of its main scientific goals is to get detailed coverage of the jovian aurorae on both northern and southern polar regions, taking advantage of the highly elliptical polar orbit of the Juno spacecraft. Among the various molecular ions that emit in the electron-driven Jupiter's aurora, H3+ is observable in the JIRAM spectral range. Its main roto-vibrational band is around 2521 1/cm, composed of more than 200 possible transitions in the range 3.0-5.0 μm; observation of the infrared emission of H3+ is mainly possible in a spectral interval (3.2 to 4.0 μm) where the solar and thermal radiance emitted by the planet are very low due to the intense atmospheric methane absorption band, resulting in a high auroral contrast against Jupiter's dark disk. Hydrocarbon emission lines are also falling in the JIRAM spectral range, thus allowing to study the morphology and variability of those emitting species. Hence, JIRAM is composed of both a 2-D IR imager and a 1-D spectrometer channel in the range 2-5 um with a spectral resolution of about 9 nm and a surface resolution as low as 50 km. One of the two imager channels is centered at 3.455 µm (in the H3+ emission region), to give a context information of auroral emission, along with the spectrometer detailed measurement. In this presentation we show the first results on JIRAM's observations of the H3+ infrared emission, taken around the first Juno pericenter (August 2016) after the orbit insertion. These observations provide spatial, spectral and temporal distribution of the Jovian auroras. Successive slant and limb observations of H3+ emission are planned and will allow the study of the vertical distribution of H3+ density and temperature profile in the thermosphere.